.box1 {
  width: 300px;
  height: 300px;
  background-color: pink;
}
.box1 .box2 {
  width: 200px;
  height: 200px;
  background-color: hotpink;
}
.box1 .box2:hover .box3 {
  background-color: lightpink;
}
.box1 .box2 .box3 {
  width: 100px;
  height: 100px;
  background-color: deeppink;
}
.box1 > .box3 {
  border: 1px solid #000;
  width: 50px;
  height: 50px;
}
